package com.fuxi;

public class fuxi_demo04 {
    public void  c(){
       final double pai = 3.14;
        int  r = 10;
        double s= pai * r *r;
        System.out.println(s);
    }

    public static void main(String[] args) {
        fuxi_demo04 f = new fuxi_demo04();
        f.c();

    }
}
